1. Field of the Invention
The present invention relates to a wired circuit board and to a production method thereof. More particularly, the present invention relates to a wired circuit board for mounting an electronic component thereon and to a production method thereof.
2. Description of the Related Art
In general, in the wired circuit board, such as a flexible wired circuit board and a suspension board with circuit, a conductive pattern of a copper foil and the like is formed on an insulating base layer of a polyimide resin, and an insulating cover layer formed of a polyimide resin is formed on the base insulating layer, to cover the conductive pattern. The wired circuit boards of this type are widely used in a variety of fields of electric and electronic equipment.
When an electronic component is mounted on this wired circuit board, the electronic component is sometimes damaged by static electricity in the mounting process.
The prior art has proposed an attempted solution, according to which for example in a flexible circuit board, a metal layer is formed on a surface of a base film or a coverlay film by vapor deposition, sputtering, or electroless plating (Cf. JP Laid-open (Unexamined) Patent Publication No. Hei 8-153940, for example).
Meanwhile, the wired circuit board has a terminal portion for mounting an electronic component. The terminal portion is formed as an exposed portion of the conductive pattern which is formed by opening the insulating cover layer so that the conductive pattern can be exposed from the opening.
In the mounting process of the electronic component, there are occasions when a certain quantity of static electricity is carried on the terminal portion (i.e., the exposed portion of the conductive pattern) as well. When the static electricity is carried on the terminal portion, there is a possibility that an electronic component mounted on the terminal portion may be damaged by the static electricity.
In the flexible circuit board described in JP Laid-open (Unexamined) Patent Publication No. Hei 8-153940, the static electricity on the base film or coverlay film on which the metal layer is formed can be removed therefrom, but the static electricity on the terminal portion cannot be removed therefrom. Thus, the prior art fails to take sufficient measures to prevent the electronic component susceptible to static electricity from the damage by the static electricity.
Also, in the flexible circuit board described in JP Laid-open (Unexamined) Patent Publication No. Hei 8-153940 cited above, since the metal layer is formed on the surface of the base film or coverlay film, there is a possibility that when a part of the metal layer is stripped, it may scatter from the flexible circuit board as a foreign matter.